Grinding/Scraping noise on 1991 740 GL when going over bumps and accelerating

[Interpage Network Services Inc.]

Hi,

Over the past year or so, I've noticed that my 1991 740 GL (rear wheel
drive) makes what can best be described as a "scraping" or grinding sound
when it goes over moderate bumps in the road and when it accelerates from a
stop.

Essentially, it sounds and "feels" (vibration-wise) like metal scraping
against concrete, and initially I thought it was the muffler or some other
low-hanging part of the car in the rear hitting the road. This theory was
re-enforced as the scraping/grinding noise was more frequent, occurred on
smaller bumps and/or less dramatic starts from a complete stop (less
acceleration) when the car was full with people or equipment as compared to
when it was empty. (IE, the heavier the car, the more scraping, so it seemed
likely that the added weight lowered the car and increased the likelihood
and duration of the scraping/grinding noise.)

However, when I took a look underneath, I didn't see anything which had
scrape or other marks which would indicate that any part of the car was
scraping against the road, which now leads me to be increasingly concerned
that it may be something more complex and/or something related to the drive
train.

(BTW, I had the transmission replaced a few months ago and this problem
pre-dated the replacement transmission, so I don't think that has anything
(directly) to do with it.)

When the car is just driving at speed, or on a very smooth road, the noise
is not heard. The only time you hear the grinding/scraping noise is on a
rough/bumpy road surface right after you go over a bump and/or when you make
a quick start from a red light or a stop sign, etc. It may also be more
prominent when accelerating uphill.

Any ideas/pointers on what I should be looking at? (After replacing the
transmission recently, I'm somewhat averse to another major investment in
the car all too soon! )

(I'm also considering getting a new S40 or a Jetta or Passat, but that's
another thread I would, however, enjoy hearing
thoughts/opinions/experiences with those cars...)

Thanks in advance for any thoughts and help!

Regards,

-Doug
Mail to: d<remove this>[email protected]
www.interpage.net
(510) 315-2750

 

[ALRHALL]

grinding sound

when it goes over moderate bumps in the road and when it accelerates from a
stop.
IE, the heavier the car, the more scraping,

A noise/vibration that increases with acceleration or heavier loading sounds
like universal joint/center bearing trouble. However I have never heard it
called a scraping noise.

Al

 

[Peter Milnes]

It is obvious that something is touching what it shouldn't. Check if exhaust
system is hanging correctly or contacting the underside of the car or the
suspension. Can also be caused by weakening springs/shock absorbers.

Cheers, Peter.

: >grinding sound
: >when it goes over moderate bumps in the road and when it accelerates from a
: >stop.
: >IE, the heavier the car, the more scraping,
:
: A noise/vibration that increases with acceleration or heavier loading sounds
: like universal joint/center bearing trouble. However I have never heard it
: called a scraping noise.
:
: Al
:
:
:
:
:
:
: